Core Steel Tester 2013

7/27/2019 Core Steel Tester 2013

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Core Steel Tester



Core Steel Testing

Powertech Transformers (PTT) is the only company

within Africa able to perform transformer core-steel

testing with Brockhaus equipment. The in-house

equipment that is available for the purpose of core-

steel testing includes the following:

Epstein Frame

The purpose of the instrument is to measure the

properties of ferromagnetic materials which are largely

used in transformers and motors. The magnetic

properties measured by the instrument include:

The B-H curve (hysteresis loop) properties as a

function of peak magnetic induction (flux density).

The B-H curve can then be used to determine the

hysteresis loss component of the material at various

flux densities.

Iron losses intrinsic to the material, at various

frequencies and peak field strengths. This allows

for the separation of the material into its key

components, namely the eddy current losses,

hysteresis losses and excess/ anomalous losses.

The excitation power requirements of the material.

This property is instrumental in determining the

magnetising current required by the material in

order to set up the magnetic flux in the core. A

higher grade core steel such as highly permeable

and domain refined electrical steels, have lowerexcitation requirements i.e. a lower excitation

current is required to set up the flux in the core.

The B8/ B800 fllux density value. This property is

a measure of the flux density resulting from a field

strength of 800A/m. This value is critical as, for

most electrical steels, it is the knee-point of the B-

H curve i.e. the value at which the B-H curve

transitions from being linear to approaching

saturation point.

This instrument has proven reliability and effectiveness

Many international standards refer to the Epstein

test such as IEC 60404-11, ASTM A717-93 and

JIS C 2550.



Single Sheet Sensor Tester (SST) 250 x 250mm

Similar to the Epstein Frame Tester, this unit measures

the magnetic properties of ferromagnetic material, with

the added capability of measuring internal stresses of

the material sustained during handling.

In addition, the Epstein Frame Tester requires at least

16 laminations, approximately 300mm x 70mm indimensions to perform a single sample test, whereas

the SST requires a single lamination, 250mm x 250mm

in dimensions. The results of the magnetic properties

measured using the SST can be converted to equivalent

Epstein Frame results; however, converting the results

of the Epstein Frame to equivalent SST is not possible.

The SST is the latest technology in core steel

measurement, but many standards still enforce Epstein

Frame Test results.

Franklin Tester

The Franklin Current Tester is used to determine the

quality aspects of the insulating material of soft magnetic

materials. This instrument is used to determine:

The maximum current permitted by the insulating

material

The surface resistance of the insulating material

per unit of area

Insulation surface resistance distribution

The thickness of the insulation coating.

Advantages of Accurate Core Steel Property

Measurements are as follows:

Material properties as guaranteed by the supplier

can be verified, reducing the frequency of deviations

in measured losses from the values guaranteed

based on material properties.

Optimisation of the core design through the use

of materials with better stacking factors

Insulation resistance measurement of samples

taken from the stacking line. This helps with the

early detection of materials with poor insulation,

thus reducing the incurrence of additional inter-

lamination losses due to short circuits between

stacked core laminations. Such losses lead to higher

no-load losses being measured during testing.

PTT is the only local South African company that can

offer core steel testing.

PTT supplies a full range of transformers, from generator

step-up to transmission and distribution transformers.

The range includes three-phase and single-phase units,

auto-transformers, arc-furnace, locomotive and traction

transformers, miniature sub-stations, NECRT's as well

as LNER’s and shunt reactors.

All operations carry ISO certifications. Both the Pretoria

and Cape Town operations have ISO 9001 -2008 quality,ISO 14001 - 2004 environmental, and OSHAS 18001-

2007 health and safety certifications. The Johannesburg

operation has the ISO 9001 - 2008 quality certification.

PTT’s laboratory is accredited for DCLF, Torque and

Temperature to IEC 17205:2005. Calibration work is

performed in-house.



Head Office

1 Buitenkant Street, Pretoria West ,PO Box 691, Pretoria, 0001, Gauteng, South Africa

Tel +27 (0)12 318 9911 Fax +27 (0)86 524 4675

Johannesburg

56 Third Street, Booysens Reserve, Johannesburg,

PO Box 38354, Booysens, 2016, Gauteng, South Africa

Tel +27 11 835 1011 Fax +27 11 835 1717

Cape Town

Elliot Avennue, Epping

PO Box 44, Eppindust, Cape Town, 7475, Western Cape,

South Africa

Tel +27 (0) 21 534 2681 Fax +27 21 534 5383

Email: [email protected]

Web: www.pttransformers.co.za

© 2013. Power Technologies (Pty) Ltd. All Rights Reserved.

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Core Steel Tester 2013